Hi Amy,
Yes, the forum seems to be popular today. An added challenge for me, too, since I'm away lecturing and so it's harder to stay on top of things. Hopefully people will cut me a little break over the next couple of weeks.
Regarding your case, I like your thinking. I think XFZYT is a fine place to start.
Check back in over the next couple of weeks. If the dog needs something else, points, pulses and symptoms that guide you should emerge by then.
If there are active GB points, or the lesion is on the TH meridian, then a formula called Chai Hu Si Wu Tang is a possibility as well. It basically moves Blood stasis due to Blood deficiency in the TH channel.
Good luck and keep us posted.
Steve